Homo erectus, also known as the
Neanderthal tribe, coexisted with the
Cromagnon tribe (which became
modern man) for quite some time. Later, when Cromagnon found out that Neanderthal was Homo erectus, Cromagnon, being very bigoted in those days, wiped out Neanderthal, or, at least, that is the majority opinion.
A minority opinion is that some men of the
Neanderthal tribe married women of the
Cromagnon tribe so as to blend in, while hiding their true nature as Homo erectus. Maybe they closed their eyes and/or turned off the lights, and imagined they were having sex with other Homo erectus, no one knows for sure. According to this opinion, the Homo erectus still live among us as a genetic variation even within otherwise Cromagnon families. Sometimes Homo erectus will even marry each other, but, like most
hybrids, they are unable to reproduce with each other, making them dependant upon Cromagnon in order to have natural children.